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GCSE AQA Chemistry > C8 - Rate of Reaction + Reversible reactions > Flashcards

C8 - Rate of Reaction + Reversible reactions Flashcards

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1
Q

rate of reaction

A

-how fast reactant turn into products

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2
Q

Work out rate of reaction

A

-measure reactants being used up
-products formed

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3
Q

Method to measure rate of reaction

A

-measure starting mass + record as it decreases as gas is lost
-measure increasing gas volume (product) in gas syringe
-measure decreasing light passing through solution = precipitate appears (product)

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4
Q

mean rate of reaction

A

quantity of reactant used/time or quantity of product formed/time

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5
Q

Tangent in reaction graphs

A

-gradient = rate of reaction
-steeper gradient = fast reaction

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6
Q

Factors that affect rate

A

-temp
-SA
-concentration of solution
-pressure of gas
-catalysts

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7
Q

collision theory

A

-when particles of reactants come together
-must collide with enough energy to react

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8
Q

activation energy

A

-minimum energy necessary for particles to react with

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9
Q

How to increase rate in terms of particles

A

-increase frequency of collisions
-increase energy of collisions

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10
Q

Increased SA in rate of reaction

A

-more substance exposed to surface
-faster reaction
-increases frequency of collisions between particles

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11
Q

Effect of temp on rate of reaction

A

-particles have more energy
-for more collisions
-more chances to react
-increases rate and reduces time

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12
Q

Increased proportion of particles with more activation energy is

A

greater effect on rate than increased frequency of collisions

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13
Q

Effect of concentration on rate of reaction

A

-increasing = faster reaction
-more particles moving in same volume
=more collisions

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14
Q

Effect on increasing pressure on rate of reaction

A

-more collisions
-less space for particles to move
-increases rate

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15
Q

catalyst

A

a substance
-increases rate of reaction
-remains chemically unchanged
-does not get used up

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16
Q

Eg of catalysts

A

-iron to make ammonia
-platinum to make nitric acid

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17
Q

physical state of catalysts and why

A

-powder form
-better SA:V
-more effective

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18
Q

How do catalysts work

A

-provide an alternate reaction pathway to product
-lower activation energy is needed
-higher proportion of reactant particles have sufficient energy to react

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19
Q

Catalysts effect on frequency of collisions

A

-increases
-increases rate

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20
Q

Pros of catalysts

A

-cheaper than using extremely high temp/pressure
-save money
-help environment as no burning of fossil fuels
-sustainable = only a little is used

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21
Q

poisoned catalysts

A

-in chemical plants
-contaminated
-is prevented from working

22
Q

reversible reaction

A

products can react to form reactants again

23
Q

Litmus paper

A

-complex molecule
-Hlit

24
Q

HLit

A

-H is for Hydrogen
-red
-add alkali = blue

25
Q

HLit add an alkali

A

Lit- ion as H is lost

26
Q

HLit can form

A

H+ and Lit -

27
Q

water of crystallisation

A

-water contained within a crystal lattice

28
Q

hydrated salt

A

-salt that contains water of crystallisation

29
Q

anhydrous salt

A

-doesn’t contain water of crystallisation

30
Q

Heating ammonium chloride

A

-thermal decomp
-forms ammonia gas and H

31
Q

Reversible reaction of ammonium chloride

A

-when heated
-2 hot gases rise in test tube
-as they cool near top, they react
-gases re-form ammonium chloride

32
Q

Energy in reversible reactions

A

-if a reaction is exothermic
-reversed reaction is endothermic
-will take in same amount of energy
-law of conservation of energy = not destroyed/created

33
Q

stages of reversible reaction - stage 1

A

-reactants only at start of reaction

34
Q

stages of reversible reaction - stage 2

A

-rate of forward reaction is greater than reverse reaction

35
Q

stages of reversible reaction - stage 3

A

-rate of reverse increases as products build up
-rate of forward reaction decreases as reactants are used up

36
Q

stages of reversible reaction - stage 4

A

rates even out
-they are the same

37
Q

as concentration of products builds up..

A

rate of reverse reaction increases
-reactants re form
-forward reaction decreases

38
Q

equilibrium

A

reactants make products at the same rate as products make reactants
-forward = backward
-no change in amount of products and reactants

39
Q

dynamic equilibrium

A

-forward + reverse reactions continuously take place

40
Q

Le chatelier’s principle

A

-lower concentration of reactants = decreases forward reaction
-changing conditions in a system of equilibrium will shift position of equilibrium to cancel out change

41
Q

conditions in Le chatelier’s principle consist of

A

-pressure
-temp
-concentration

42
Q

Why is Le chatelier’s principle important in industry

A

-chemists must find condition that produces most products in shortest amount of time

43
Q

if the forward reactions produces more gas molecules ..

A

-increase in pressure decreases products formed
-decrease in pressure increases products

44
Q

if forward reaction produces fewer gas molecules..

A

-increase in pressure increases products
-decrease in pressure decreases products

45
Q

when there are equal numbers of molecules of gas on both sides of equation ..

A

-pressure cannot affect composition of equilibrium mixture
-but will speed up reaction in equal amounts

46
Q

change in temp in a closed system

A

-more products
-less reactants

47
Q

if forward reaction is exothermic

A

-increase in temp decreases products
-decrease in temp increases products

48
Q

if forward reaction is endothermic

A

-increase in temp increases products
-decrease in temp decreases products

49
Q

affect of increase in temp on equilibrium

A

-it shifts to reduce the temp

50
Q

increasing temp favours which reaction

A

endothermic

51
Q

decreasing temp favours which reaction

A

exothermic

GCSE AQA Chemistry (36 decks)

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